Standards · ASME and ASTM · ASTM A350/A350M
ASTM A350/A350M: Carbon and low-alloy steel forgings requiring notch toughness testing for piping components
The low-temperature sister of A105: forged flanges, fittings and valve parts whose notch toughness is tested at the design temperature – the forging that belongs to A333 pipe and A420 fittings.
- Issued by
- ASTM
- Edition (publisher, as of 2 October 2026)
- 2026a
- Material specification
- Carbon and low-alloy steel forgings requiring notch toughness testing for piping components
- European counterpart
- EN 10222-4 (P285NH 1.0477, P285QH 1.0478, P355QH1 1.0571) / EN 10222-3 (12Ni14 1.5637)
- Belongs with
- ASME B16.5 · ASTM A105/A105M · ASTM A333/A333M · ASTM A420/A420M
- At Zickwolff
- we carry – from stock or to order, lead time on request
Scope: sizes, classes, grades
Grades LF1, LF2, LF3, LF5, LF6, LF9 and LF787. LF2 Class 1 is the standard: impact test at −46 °C (−50 °F), average min. 18 J, tensile 485 to 655 MPa, yield min. 250 MPa, otherwise the strength of A105. LF1 is tested at −29 °C, LF3 (3.5 % Ni) at −101 °C, LF2 Class 2 at −18 °C with higher energy.
Product form
Forged or ring-rolled flanges, fittings and valve parts, also parts machined from bar or seamless pipe.
Grades and their European counterparts
| Grade | Type | Impact test at | Tensile / yield min. (MPa) | European counterpart | Limits of the comparison | At Zickwolff |
|---|---|---|---|---|---|---|
| LF1 Cl. 1 | low-temperature steel | −29 °C | not stated in our sources | not stated in our sources | no common EN grade – compare by analysis and certificate | on request |
| LF2 Cl. 1 | low-temperature steel | −46 °C | 485 / 250 | P285NH / P285QH (Gruppe), P355QH1 (Handel) 1.0477 / 1.0478 / 1.0571 · EN 10222-4 | comparable low-temperature steel, impact test temperature and energy differ | deliverable |
| LF2 Cl. 2 | low-temperature steel | −18 °C | 485 / 250 | P285NH / P285QH 1.0477 / 1.0478 · EN 10222-4 | comparable low-temperature steel, impact test temperature and energy differ | on request |
| LF3 Cl. 1 | low-temperature steel | −101 °C | not stated in our sources | 12Ni14 1.5637 · EN 10222-3 | comparable low-temperature steel, impact test temperature and energy differ | on request |
EN 1092-1 places LF2 in the group of P285NH and P285QH to EN 10222-4, trade lists LF2 beside P355QH1, LF3 corresponds to 12Ni14 to EN 10222-3.
Use in Europe: the Pressure Equipment Directive
Under the Pressure Equipment Directive an ASTM material has no presumption of conformity: it needs a European material approval or a particular material appraisal (PMA) by the equipment manufacturer, in categories III and IV assessed by the notified body. Comparisons with EN grades are orientation, never a one-to-one equivalence – chemistry bands, test scope and certificate differ. LF2 and A105 share the strength but not the toughness proof – a stamp LF2 without the impact values on the certificate is worthless for the designer.
Marking on the part
On the flange: manufacturer, NPS, Class, A350 or SA-350 with LF2 (and class), heat code, B16.5.
The standard family: dimensions, material, pipe
ASME B16.5 · ASTM A105/A105M · ASTM A333/A333M · ASTM A420/A420M
At Zickwolff
Flanges A350 LF2 to B16.5 are part of our range for low-temperature lines, LF3 we procure – with certificate 3.1 including impact values – A105 remains the choice above −29 °C.
Dimensions Dimension tables for this standard are on our page flange dimensions ASME B16.5. For the weld neck flange there is also a dimensional drawing with tolerances for each class and NPS: weld neck flange ASME B16.5.
Further reading
The profiles: ASME B16.5 · ASME B16.9 · ASME B16.25 · ASME B36.10M · ASME B36.19M · ASTM A105/A105M · ASTM A106/A106M · ASTM A182/A182M · ASTM A234/A234M · ASTM A333/A333M · ASTM A403/A403M · ASTM A420/A420M · ASME and ASTM standards.
From our pages: Flange dimensions ASME B16.5 Class 150/300 · DIN/EN or ASME for flanges · Standards guide · Materials · Pipe dimension tables · Rule of thumb: Class 150 is not 150 psi · Rule of thumb: schedule is not a wall thickness · Rule of thumb: DN is not a diameter.
Frequently asked questions about ASTM A350/A350M
Can I use this ASTM material in a pressure line under the PED?
Yes, but without presumption of conformity: the equipment manufacturer needs a European material approval or a particular material appraisal (PMA), in categories III and IV assessed by the notified body. For equipment under Article 4(3) (sound engineering practice) this does not apply. We supply the material with certificate 3.1 – the appraisal is the manufacturer's.
Must a plant with ASME parts be inspected more often?
No – the inspection interval comes from the operating law of the country, not from the code of the part. In Germany the Betriebssicherheitsverordnung (Annex 2 Section 4) sets maximum intervals, the operator fixes the interval in the risk assessment and the inspector may shorten it (TRBS 1201 Part 2) where design or manufacture give reason to. Operators often inspect more frequently anyway. This is general information, not legal advice – the legal text is binding.
LF2 Class 1 or Class 2?
Class 1 is tested at −46 °C with 18 J average, Class 2 at −18 °C with higher energy – Class 1 is the usual low-temperature flange.
Is LF2 stronger than A105?
No – same tensile and yield minimum. The difference is the proven toughness at low temperature and the upper limit of 655 MPa.
Parts to ASME and ASTM – from one source
Tell us standard, size (NPS and schedule or Class), material grade, certificate and quantity – we check what is in stock, what we procure and which European part would do the same job.
Send an inquiryYour inquiry to Zickwolff
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Designation, standard and quantity are enough.
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Attach it as a file.
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Tell us by when you need the material – we will tell you what is possible.
Basis: the publicly accessible scopes and abstracts of ASME and ASTM (editions as of 2 October 2026), manufacturer catalogues, a trade reference catalogue DIN/EN/ASME and specialist sources for marking and impact test values – the legal statements follow Directive 2014/68/EU and the German Betriebssicherheitsverordnung. No standard text was reproduced – the current original edition is binding. Comparisons with EN grades are orientation, not equivalence. Information without guarantee, no legal advice, no prices.